This disclosure relates to a homing tool for a coating platter and, more particularly, to a homing tool for a platter that supports turbine engine components for a coating process.
Certain gas turbine engine components are subject to a coating application during manufacture, such as a cathodic arc coating for example. A tooling fixture is used to support multiple components such that the coating is evenly applied over all desired areas. The tooling fixture includes a fixed platter and a large central gear that rotates relative to the platter. Several tooling sites with locating features are supported on the gear. The tooling sites and the central gear are connected in such a way that rotating the central gear about its axis will also rotate the tooling sites about their axis. Shielding is attached to the platter assembly for protective purposes. The tooling fixture and associated components are placed onto the tooling sites on the central gear. The platter is placed within the coater apparatus and the coating is applied.
In order to ensure that the components are fully and evenly coated, the gear must be “homed” or aligned properly. If the gear is not aligned properly prior to the coating process, then the tooling sites will not be in the correct position. As the cathodic arc coating process is a line of sight coating process, if the components are improperly aligned, deposition of the coating could be uneven.
One example of a tool that has been used to check alignment is a locating plate. To check whether there is proper alignment, the shielding is removed and then the locating plate is bolted into place. The locating plate includes three holes. One hole is to be aligned with a hole in the gear, and the other two holes are to be aligned with two holes in the platter. If all of the corresponding holes are in alignment with each other, then the platter is supposedly homed. However, if the gear has been rotated 180 degrees, the locating plate will still fit on the platter and the gear but the homing is incorrect and the tooling sites and thus the components are not in the correct position on the gear.
Another disadvantage with the use of the locating plate is that the shielding must be removed prior to attachment of the locating plate. As such, this homing operation cannot be accomplished between coating runs due to the high heat that the tooling fixture components are subjected to during the coating process. To perform the homing operation, the tooling fixture components need to cool sufficiently such that all of the shielding can be removed, then the platter is removed from the coating machine, and then the locating plate is mounted to the platter and the gear to check for alignment. This alignment check process could take over 30 minutes to perform.
Accordingly, there is a need for a method and apparatus to check for proper alignment that addresses the problems identified above.